public BigInteger NextPrime(int sizeBytes)
{
BigInteger testNum = Next(sizeBytes);
if (testNum % 2 == 0)
{
testNum--;
}
BigInteger current = testNum;
bool failed = false;
while (!BigIntegerPrimeTest.MillerRabinTest(current))
{
if (current.ToByteArray().Length == sizeBytes)
{
current -= 2;
}
else
{
failed = true;
break;
}
}
if (!failed)
{
return(current);
}
else
{
current = testNum + 2;
while (!BigIntegerPrimeTest.MillerRabinTest(current))
{
current += 2;
}
}
return(current);
}
//Ро- метод Полларда
public static List <BigInteger> PollardsAlg(BigInteger n)
{
var result = new List <BigInteger>();
if (BigIntegerPrimeTest.MillerRabinTest(n))
{
return(result);
}
BigInteger N = n;
BigInteger i = 1;
BigInteger nextiToSave = 1;
Random rand = new Random();
BigInteger x = RandomBigInteger(n, rand);
BigInteger y = 1, lastx = 1;
BigInteger res = 0;
while (N % 2 == 0)
{
if (!result.Contains(2))
{
result.Add(2);
}
N /= 2;
}
while (!BigIntegerPrimeTest.MillerRabinTest(N))
{
BigInteger factor;
BigInteger delta = BigInteger.Abs(x - y);
if (delta == 0)
{
x = RandomBigInteger(n, rand);
i = 0;
nextiToSave = 1;
y = 1;
lastx = 1;
continue;
}
BigInteger gcd = BigInteger.GreatestCommonDivisor(N, delta);
lastx = x;
x = (x * x - 1) % n;
if (i == nextiToSave)
{
nextiToSave *= 2;
y = lastx;
}
i++;
if (gcd > 1)
{
factor = gcd;
if (!BigIntegerPrimeTest.MillerRabinTest(factor))
{
var factorFactors = PollardsAlg(factor);
foreach (var item in factorFactors)
{
result.Add(item);
}
}
else
{
if (factor > 1)
{
result.Add(factor);
}
}
N /= factor;
}
}
if (N > 1 && !result.Contains(N))
{
result.Add(N);
}
result.Sort();
return(result);
}